Environmental Engineering Reference
In-Depth Information
Figure 14.16
Fluvial sediment entrainment.
Figure 14.17
Sediment routeing through the catchment.
profile, along which potential energy increases exponentially towards the source, was
once used to distinguish between vigorous, youthful headwaters and sluggish, senile
lowland rivers. However, both elements are present in mature, integrated catchments. The
profile corresponds to a power curve requiring constant adjustment by the river to
downstream changes in potential energy, discharge, slope and sediment load. Locally,
surplus energy erodes and lowers the profile through
incision
, whereas energy deficit
leads to its
aggradation
or elevation through deposition. At any time the profile is
complicated by different stages of response to tectonic and eustatic changes in base level,
climatic, geological and land-use conditions and - increasingly - human regulation of the
catchment.
UPPER CATCHMENTS AND BEDROCK CHANNELS
Bedrock channels and associated valleys are not confined to mountains or uplands,
although tectonic drive and denudation produce some of Earth's deepest gorges and rock-
